I. Field of the Invention
This invention relates generally to the design of ventilation tubes for medical applications and more particularly to a ventilation tube for placement in the region of the nasal sinuses following endoscopic antrostomy. The presence of the tube retards scarring and adhesion; thus, it promotes healing and lessens post-operative complications.
Functional endoscopic sinus surgery, or antrostomy, is becoming increasingly popular in the treatment of chronic nasal and paranasal sinus disease. Following such surgery, the middle turbinate, a structure within the nasal cavity, has a tendency to move laterally towards the lateral nasal wall. During an irritated, post-surgical state, this movement promotes synechiae (adhesion) formation, whereby normally freely hanging structures become physically adhered to other structures adjacent to the sinuses. This can subsequently result in increased susceptibility to renewed infection of the osteomeatal complex. Obstruction can also occur, as the tissues become increasingly adhered to one another.
To prevent lateral movement of the middle turbinate and reduce the possibility of such synechiae formation, a stent can be placed between the middle turbinate and the lateral nasal wall to hold them apart until sufficient healing has occurred in the area that the conditions which promote synechiae formation have subsided. Thus, the presence of the stent will prevent adhesion or synechiae formation. The stent will also function as a ventilation tube that will maintain the patency of the middle meatal antrostomy and promote aeration and drainage of the sinuses. The use of a post-operative stent also furthers the goals of the surgery to restore mucociliary clearance and prevent osteopathology.
II. Discussion of the Prior Art
An externalizing shunt disclosed in U.S. Pat. No. 4,534,761 to Raible. It consists of an unobstructed passageway having an annular rim and an anchor of grafting mesh positioned midway along the outer circumference of the device. It is formed from either pyrolytic or vitreous carbon over a graphite substrate. The exterior surfaces, including the grafting mesh, are coated with collagen in order to enhance adhesion to the surrounding tissues. There is no indication of the dimensions of the device, but the anchor includes a plurality of apertures that essentially span the width of the anchor and receive suture material or otherwise stabilize the device.
Shunts are commonly used in other medical applications. They are commonly used to ventilate the inner regions of the ear. Such ear tubes are shown in U.S. Pat. Nos. 4,744,792, 4,704,126 and 4,650,488. The U.S. Pat. No. '792 patent to Sander, et al. discloses a fluoroplastic polymer coated titanium or titanium alloy ventilation tube with spaced apart flanges. The flange that will be adjacent the outer ear canal may have a plurality of radially spaced openings which facilitate insertion by providing sites that may be grasped by a forceps. An optional bore liner is provided to promote the ingrowth and adhesion of tissue. The U.S. Pat. No. '126 patent to Baswell discloses a similar titanium or titanium alloy ear tube implant. Rather than having a biocompatible fluoroplastic coating, the exterior surfaces of the Baswell U.S. Pat. No. '126 device are polished to a smooth, matte finish.
U.S. Pat. No. 4,650,488 to Bays, et al. discloses an implant made of a biodegradable material. It is dimensioned for implantation between the middle and inner ear. To aid in insertion, one region of the outer flange has a tab which extends perpendicular to the surface of the tympanic membrane and can be grasped with a forceps, hemostat or similar device.
The shunts disclosed in the U.S. Pat. No. '792, '126 and '488 patents are all composed of inflexible or brittle materials that are not well suited to bending or, if bent, lack a memory capacity to return them to their original configuration. Due to a desire to minimize the degree of invasion into nasal tissue, it is desirable to utilize an elastomeric material that can be coaxed into proper position using a slit in the tissues having minimal dimensions. A flexible elastomer is also thought to be less traumatic, producing less abrasion of surrounding tissues during and after insertion.
It is accordingly a principal object of the present invention to provide a new and improved ventilation tube that will physically separate structures within the sinuses and thus promote post-surgical recovery.
Another object is to provide a ventilation tube for us in antrostomy procedures to enhance aeration and drainage of the post-surgical region.
Yet another object is to provide a middle meatal ventilation tube that will mechanically separate the middle turbinate and the lateral nasal wall during the post-surgical recovery period and thus prevent the formation of synechiae and other adhesions.
A further object is to provide a middle meatal ventilation tube that is composed of relatively atraumatic elastomeric material in order to minimize tissue damage.
Another principal object of the invention is to provide a method for properly inserting the ventilation tube.